Method and system for measuring multiple soil properties

ABSTRACT

A method and system for measuring multiple soil properties on-the-go is provided on an implement for traversing a field. An optical module is carried by the implement for collecting soil reflectance data. A pair of soil contact blades protrude from or are embedded in the optical module for collecting soil EC data and soil moisture data. A switching circuit or phase lock loop allows the same soil contact blades to feed signals to both a soil EC signal conditioning circuit and a soil moisture signal conditioning circuit. The soil moisture data can be used to calibrate the soil EC data and the soil reflectance data to compensate for effects of changing soil moisture conditions across a field. The system can also be used on a planter to control planting depth and/or seeding rate in real time based on multiple soil properties collected during planting.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/812,131 filed on Apr. 15, 2013. The entire content ofthe priority application is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates generally to methods and systems formeasuring multiple soil properties at various depths across a field, andto systems and methods for using such soil property measurements toimprove various processes, such as variable rate irrigation, soilmapping, and planting.

Description of the Related Art

Soil moisture is a major driver of crop production, particularly in aridregions. Soil moisture varies spatially within fields due to soiltexture, topography, crop usage, irrigation patterns, and various othervariables.

Fixed, semi-permanent moisture sensors (e.g., gypsum blocks and neutronprobes) and manually inserted sensors (e.g., TDR, capacitance) have beenused for many years to monitor soil moisture levels in agriculturalfields. However, these moisture sensors do not capture the spatialvariability as their expense and manual deployment make it unfeasible tocollect enough measurements to produce a spatially accurate map of soilmoisture.

Variable rate irrigation allows limited irrigation water supplies to beapplied at different rates in different areas of a field. For example,variable rate irrigation can be used to apply more irrigation water tozones of a field where water holding capacity is lower or where crop useor productivity is expected to be greater. Fixed moisture sensors areoften used in fields with variable rate irrigation. However, the use offixed moisture sensors does not link soil moisture with soil propertiesthat affect water-holding capacity and crop usage of water.

Systems and methods are known for measuring soil electrical conductivity(EC) and soil color (reflectance). For example, the Applicant'scopending application Ser. No. 13/277,208 filed on Oct. 19, 2011, for aninvention titled “MOBILE SOIL OPTICAL MAPPING SYSTEM” provides a systemfor measuring soil reflectance values and using the soil reflectancedata to determine and map soil organic matter (OM). For another example,Applicant's copending Application No. 61/774,559 filed on Mar. 7, 2013,for an invention titled “METHOD AND SYSTEM FOR CLASSIFYING SOILPRODUCTIVITY” provides a system for analyzing and using data collectedfrom on-the-go soil EC and soil reflectance sensors. The contents ofthese prior applications are hereby incorporated herein by reference.

Soil EC relates to soil texture and soil moisture. Soil opticalmeasurements relate to soil OM and soil moisture. Increasing levels ofsoil moisture increase soil's ability to conduct electricity and makethe soil appear darker. The presence of soil moisture, especially whenits variations do not spatially correlate with soil texture and soil OM,can confound soil EC and optical sensing of soil texture and soil OM.Soil EC and soil color sensors have been developed and are being used torelate to soil texture and organic matter, but no system or methodexists for accounting for the contribution of soil moisture.

Typical planting depths for agricultural crops, such as corn, are 1.5 to2.5 inches. The grower's objective is to place seed into warm, moistsoil at a consistent depth to achieve uniform emergence. Germination andemergence are optimized when depth is consistent and seeds are placed inthe optimal combination of warm and moist soil.

However, moisture and temperature vary spatially within fields andwithin the top 3 inches due to soil texture, topography, crop usage,irrigation patterns, residue cover, and a variety of other factors.Growers must occasionally compromise one factor for another, e.g.,planting deeper into colder soil than desirable in order to have seed inmoist soil.

There is a need for a method and system for on-the-go sensing of soilmoisture, soil EC and other properties, and for using those measurementsto improve various processes, such as variable rate irrigation, soilmapping, and planting.

SUMMARY OF THE INVENTION

A method and system for measuring multiple soil properties on-the-go isprovided on an implement for traversing a field. An optical module iscarried by the implement for collecting soil reflectance data. A pair ofsoil contact blades protrude from or are embedded in the optical modulefor collecting soil EC data and soil moisture data. A switching circuitor phase lock loop allows the same soil contact blades to feed signalsto both a soil EC signal conditioning circuit and a soil moisture signalconditioning circuit. The soil moisture data can be used to calibratethe soil EC data and the soil reflectance data to compensate for effectsof changing soil moisture conditions across a field. The system can alsobe used on a planter to control planting depth and/or seeding rate inreal time based on multiple soil properties collected during planting.

According to one aspect of the present invention, a system for measuringsoil moisture on-the-go is provided, comprising: an implement fortraversing a field; at least one soil contact member carried by theimplement, the at least one soil contact member being arranged forcontacting soil as the implement traverses the field; and a moisturesignal conditioning circuit connected to the soil contact member tocollect soil moisture data from soil contacted by the soil contactmember.

According to another aspect of the present invention, a system formeasuring multiple soil properties on-the-go is provided, comprising: animplement for traversing a field; an optical module carried by theimplement for collecting soil reflectance data from soil in the field; asoil EC measurement device carried by the implement for collecting soilEC data from soil in the field; a soil moisture measurement devicecarried by the implement for collecting soil moisture data from soil inthe field; and the optical module, soil EC measurement device and soilmoisture measurement device are arranged to measure soil reflectance,soil EC and soil moisture at approximately the same depth and in closeproximity to the optical module.

According to another aspect of the present invention, a system formeasuring soil properties on-the-go is provided, comprising: animplement for traversing a field; a sensor carried by the implement formeasuring at least one soil property, the sensor comprising at least oneof an optical module for collecting soil reflectance data, a soil ECmeasurement device for collecting soil EC data, and a soil moisturemeasurement device for collecting soil moisture data; and a means formeasuring a depth of operation of the sensor on-the-go while the sensoris measuring the at least one soil property.

According to another aspect of the present invention, a system formeasuring multiple soil properties on-the-go is provided, comprising: animplement for traversing a field; and at least one soil contact membercarried by the implement, the at least one soil contact member beingarranged for collecting both soil EC data and soil moisture data fromsoil in the field.

Numerous other objects of the present invention will be apparent tothose skilled in this art from the following description wherein thereis shown and described embodiments of the present invention, simply byway of illustration of some of the modes best suited to carry out theinvention. As will be realized, the invention is capable of otherdifferent embodiments, and its several details are capable ofmodification in various obvious aspects without departing from theinvention. Accordingly, the drawings and description should be regardedas illustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more clearly appreciated as thedisclosure of the present invention is made with reference to theaccompanying drawings. In the drawings:

FIG. 1 is a side elevation view of an implement equipped with a systemfor measuring multiple soil properties according to the presentinvention.

FIG. 2 is a side elevation view of a row unit of the implement shown inFIG. 1.

FIG. 3 is a lower left side perspective view of a row unit equipped withsensors for providing on-the-go measurements of soil moisture, soil EC,soil reflectance, and depth according to the present invention.

FIG. 4 is a diagram showing the basic circuit components of the systemfor measuring soil moisture, soil EC, and soil reflectance according tothe present invention.

FIG. 5 is a perspective view of a group of rolling coulters that can beused to provide additional sets of soil contact members for collectingsoil EC and soil moisture data.

FIG. 6 is a side elevation view of a row unit equipped with a system formeasuring multiple soil properties according to the present invention.

FIG. 7 is a side elevation view of a planter row unit equipped with asystem for measuring multiple soil properties for use in adjustingplanting depth and/or seeding rate in real time according to the presentinvention.

FIG. 8 is a side elevation view of a furrow opener assembly of a planterrow unit having a sensor module combined with a seed tube guard locatedbetween the furrow opener disks.

FIG. 9 is a rear elevation view of the furrow opener assembly shown inFIG. 7.

FIG. 10 is a diagram of a control system for an agricultural planter forvarying seeding rate and planting depth based on soil propertiesmeasured by sensors carried by the planter.

FIG. 11 is a flowchart of an algorithm used by the control system forvarying planting depth.

FIG. 12 is a flowchart of an algorithm used by the control system forvarying seeding rate.

DETAILED DESCRIPTION OF THE INVENTION

A method and system for measuring multiple soil properties according tothe present invention will now be described in detail with reference toFIGS. 1 to 12 of the accompanying drawings.

FIGS. 1 to 3 illustrate an implement 10 having a specially configuredrow unit 11 for measuring multiple soil properties according to thepresent invention. The implement 10 includes a coulter 13 for cuttingthrough residue and for opening a slot in the soil. The row unit 11includes a furrow opener assembly 14 that creates a furrow in the soil,and a sensor module 15 containing sensors for measuring multiple soilproperties. The row unit 11 can be mounted to a toolbar 17 of theimplement 10 by a parallel linkage 18 that allows the furrow opener 14and sensor module 15 to follow ground undulations while maintaining aconsistent depth in the soil. A plurality of springs 19 or a pneumaticsystem (not shown) can be used to provide an adjustable down-force tomatch soil conditions.

The furrow opener 14 in the illustrated embodiment includes two disks 20that penetrate and follow in the slot created by the leading coulter 13.The disks 20 are arranged at a slight angle relative to a direction oftravel so as to form a V-shaped slot or furrow in the soil. For example,the furrow opener 14 can be constructed in the same manner as aconventional double disk furrow opener used in an agricultural planter.Other types of furrow openers may also be used with the presentinvention.

A pair of gauge wheels 21 are mounted in close proximity to the furrowopener disks 20 to control the operating depth of the disks 20 and toscrape off any soil that adheres to the outer surfaces of the disks 20during operation. The gauge wheels 21 are mounted together with thefurrow opener disks 20 and the sensor module 15 on a subframe 22 of therow unit 11. The gauge wheels 21 maintain a consistent depth of thesensor module 15 in the soil during operation. For example, the gaugewheels 21 can be adjusted relative to the furrow opener disks 20 andsensor module 15 to allow measurements to be taken at selected depths ofapproximately 1 to 3 inches below the soil surface.

A furrow closing assembly 23 follows along behind the sensor module 15to close the furrow after soil measurements are taken with the sensormodule 15 to prevent erosion. The furrow closing assembly 23 can be apair of closing wheels 25 as shown in FIGS. 1 and 2, or a pair ofclosing disks or other suitable closing members.

The sensor module 15 is mounted between the two furrow opener disks 20and is pressed against the bottom of the furrow while measurements arebeing made. The sensor module 15 includes an optical module 15 a at itsfront portion and a soil moisture and soil EC module 15 b at its rearportion. The sensor module 15 has a hardened wear plate 15 w on itsbottom surface that presses against the soil within the furrow duringoperation. The wear plate 15 w can be provided in two parts with a frontpart covering the bottom of the optical module 15 a and a rear partcovering the bottom of the soil moisture and soil EC module 15 b. Thefront part of the wear plate 15 w contains a sapphire window 16 forobtaining soil reflectance measurements. The consistent pressure of thesensor module 15 against the soil provides a self cleaning function thatprevents a buildup of soil on the window 16.

As illustrated in FIG. 4, the optical module 15 a includes a singlephotodiode 30, a borosilicate photodiode protection window 31, twodifferent wavelengths of modulating monochromatic light sources 32, 33modulated at different frequencies, and the sapphire window 16 in thewear plate that presses against the soil within the furrow. Themodulated light is directed from the two light sources 32, 33 throughthe sapphire window 16 onto the soil. The reflected light is thenreceived by the photodiode 30, converted to a modulated voltage, andsent to a signal conditioning circuit 38 in the controller 36. Thephotodiode 30 is hermetically sealed with the borosilicate window 31protecting the surface. This allows for easy cleaning and is robust foroutdoor use.

The controller 36 includes two function generators 37 for generating themodulated light from the two light sources 32, 33, the signalconditioning circuit 38 including a phase lock loop (PLL) to separateeach source of reflected light from the photodiode signal, an analog todigital (A/D) converter 39, and a serial output 40 for data logging.

The function generators 37 send two separate pulses; one goes to thefirst wavelength light-emitting diode (LED) 32, the other to the secondwavelength LED 33. These pulses are directed at the soil through thesapphire window 16. The light reflected off the soil is read by thephotodiode 30 and converted into a modulated voltage. The modulatedvoltage from the photodiode 30 is processed through the signalconditioning circuit 38, which converts the modulated voltage to a DCvoltage. The DC voltage is processed through the A/D converter 39, thenthe output is sent through the serial output 40 to the DataLogger or PC41. The data is georeferenced using a GPS signal from a GPS receiver 42connected to the DataLogger or PC 41.

By modulating the LEDs 32, 33 at two separate known frequencies andsending the modulated photodiode voltage to the PLL 38, each LED signalcan be extracted individually from the photodiode signal, withoutreceiving interference from the other LED light source or ambient light.This allows for a clean signal of only the reflected light of each LEDto be stored, free from any outside interference.

Correlating sensor data to soil properties requires the development ofcalibration equations. Previous calibration attempts with simple opticaldevices have relied on bivariate regression, with the optical data asthe sole sensor variable. One of the situations that can confoundoptical measurements of organic matter is soil moisture that relates tosoil texture variations in addition to relating to organic mattervariations.

The present invention includes the use of soil contacting members 15 cfor collecting soil EC and soil moisture data in close proximity and atapproximately the same depth as the optical module 15 a. The soilcontacting members 15 c can protrude from the sensor module 15, or thesoil contacting members 15 c can be embedded in poly or othernon-conductive material so that they are flush with an outer surface ofthe sensor module 15 b. The soil contacting members 15 c can be a pairof soil contacting blades, as in the illustrated embodiment, or therecan be more than two (e.g., 3 or 4) soil contacting surfaces on thesensor module 15 or blades protruding from the sensor module 15. Thesoil contacting members 15 c can also be a single soil contacting bladein combination with the metal housing of the sensor module 15 serving asthe other soil contacting member. The soil contact members 15 c arepreferably arranged so that they are pressed into or against the soil tomake good soil contact.

In the illustrated embodiment, the soil contacting members 15 c comprisea pair of spaced apart metal blades that protrude downwardly from thebottom surface of the rear part of the wear plate 15 w. The soilcontacting members 15 c are pressed into or against the soil to measurethe soil EC and soil moisture at approximately the same depth as thesoil reflectance measurements are collected by the optical module 15 aas the implement 10 travels across the field.

Soil EC has been proven to correlate well with soil texture. Soil EC andsoil reflectance data can be used together to help resolve organicmatter variations in the field. However, both soil EC and soil opticalmeasurements are affected by soil moisture; increased soil moisturecauses higher EC conductance and reduces optical reflectance. Soilmoisture typically varies spatially within a field and with depth. Indry conditions, the moisture increases with depth; however following aprecipitation event the opposite may be true. In order to improvecalibrations to soil texture and cation exchange capacity (CEC), whichtypically correlate to soil EC, effects of moisture need to be accountedfor. Similarly, soil OM predictions from optical sensors can be improvedby accounting for soil moisture. In the present invention, soil moisturedata is used by the controller 36 to calibrate the soil EC and soilreflectance measurements to account for the effect of soil moisturevariations on the soil EC and soil reflectance data.

The soil contacting members 15 c are used to collect both soil EC andsoil moisture data. In one embodiment, a switching circuit 50 isconnected to the soil contact members for automatically switching backand forth between a soil EC conditioning circuit 51 and a soil moistureconditioning circuit 52. The soil EC conditioning circuit 51 maycomprise, for example, dipole circuitry, while the soil moistureconditioning circuit 52 may comprise, for example, capacitance circuitryusing frequency domain reflectrometry (FDR) measurement. The switchingcircuit 50 allows both soil EC and soil moisture readings to becollected from the same soil contact members 15 c. The switching circuit50 can be set to switch back and forth rapidly between the soil EC andsoil moisture conditioning circuits to collect both soil EC and soilmoisture readings virtually simultaneously.

Other circuit arrangements can be made to collect both soil EC and soilmoisture data from the soil contact members 15 c. For example, a phaselock loop can be connected to the soil contact members 15 c forcapturing both soil EC and soil moisture readings simultaneously.

The soil contact members 15 c on the bottom of the wear plate 15 w aremost suitable for contacting the soil at a shallow depth, e.g., 1 to 3inches. One or more additional sets of soil contact members (not shown)can be used to make soil EC measurements on a separate circuit from thefirst set of soil contact members 15 c. In this case, the first set ofsoil contact members 15 c can be used to collect soil moisturemeasurements, and the second set of soil contact members can be used tocollect soil EC measurements. In this configuration, the soil moisturecontact members 15 c are on a separate circuit from the soil EC contactmembers, and there is no need for the switching circuit or phase lockloop 50.

Additional sets of soil contact members can also be added to theimplement 10 to collect soil EC and soil moisture data from differentdepths. For example, multiple sets of metal blades, such as rollingcoulter blades 63 (FIG. 5), can be arranged on the implement 10 tocontact the soil at a greater depth than the first set of soil contactmembers 15 c to collect soil EC and soil moisture readings from multipledepths as the implement 10 traverses the field.

A soil temperature sensing device 53 is also arranged in the sensormodule 15. The soil temperature sensing device 53 may include, forexample, a thermocouple or infrared temperature sensor positioned in oron the wear plate 15 w of the sensor module. The temperature sensingdevice 53 is preferably arranged to collect soil temperature data fromthe soil at approximately the same depth as the soil EC and soilmoisture data are collected. Soil EC values increase with increased soiltemperature, so accounting for temperature variations can improvecalibrations to soil texture and soil CEC. Soil temperature can also beused in conjunction with a system for on-to-go sensing of soilproperties during planting, as further explained below.

The sensor row unit 11 includes a means for monitoring and controlling adepth of operation of the furrow opener 14. This means includes a depthsensor gauge wheel mount 54, a mechanical depth sensor linkage 55, and adepth sensor 56. The depth sensor 56 can be, for example, an opticalencoder or a rotary or linear potentiometer sensor that provides asignal to the controller 36 based on the angle of rotation of the sensorlinkage 55. The sensor row unit 11 can also include an adjustabledownpressure system or a remote depth adjustment mechanism 57 (FIG. 6)to vary the operating depth of the furrow opener 14 to adjust the depthof soil measurements. In the illustrated embodiment, the depthadjustment mechanism 57 includes an actuator 58 and linkage 59 coupledto an adjustment arm on the planter row unit 61.

As the sensor row unit 11 moves through the field, undulations and soilclods may cause the row unit depth 11 to vary. The depth sensor 56records the depth at which all optical, EC and moisture measurements arecollected, which allows these measurements to be evaluated and erroneousones removed.

The data received from the optical measurement device 15 a, the soil ECmeasurement device 15 c, 51, the soil moisture measurement device 15 c,52, the soil temperature measurement device 53, and the soil depthmeasurement device 56 are all georeferenced using the GPS signal fromthe GPS receiver 42 connected to the DataLogger or PC 41. Each datapoint will include a latitude/longitude value, a sensor operating depth,and the sensor values. The controller 36 is programmed to create ageoreferenced map of these data points for multiple soil properties asthe implement 10 traverses the field and collects the data. Thecontroller 36 can also be programmed to automatically cycle the sensorrow unit 11 to vary the depth of operation of the sensor module 15on-the-go. This will allow one sensor row unit 11 containing the sensormodule 15 to collect dense data of multiple soil properties at multiple,discrete depths. This will also improve estimations of soil OM becausethe calibrations would include sensor readings from multiple depths.

The depth sensor 56, depth adjustment mechanism 57, and depth cyclingfeature of this invention can be used for all of the sensors (e.g.,optical, EC, moisture, and temperature) carried by the sensor module 15.Alternatively, the depth sensor and depth cycling feature could be usedfor any one of these sensors individually. For example, an implementhaving an optical module with an optical sensor (with or without theother sensors) would benefit from having the depth sensor and depthcycling feature, which would improve quality control and provideadditional reflectance data at multiple depths for analysis. Similarly,an implement having a soil EC sensor and/or a soil moisture sensor couldbe equipped with the depth sensor and depth cycling feature of thepresent invention.

The controller 36 can also include an algorithm to determine availablewater holding capacity of the soil based on the measured soil EC, soilreflectance, and soil moisture. The water holding capacity will providea useful measure for scheduling irrigation, and particularly forvariable rate irrigation in fields with large spatial variations inwater holding capacity. The water holding capacity will also provide auseful metric for varying seeding population because water holdingcapacity can be a good indicator of soil productivity. Linking moisturesensing with sensors that relate to soil texture and organic matter,which affect water-holding capacity and crop usage of water, willprovide additional synergistic information that individual moisturesensors are unable to do alone.

An agricultural planter 60 equipped with the system for measuringmultiple soil properties will now be described with reference to FIGS. 7to 12. The planter 60 includes at least one planter row unit 61 having afurrow opener 14 for creating a furrow, and a seed metering mechanism 62for singulating and depositing seeds through a seed tube T into thefurrow. The planter row unit 61 includes depth gauge wheels 21 thatcontrol a depth of operation of the furrow opener 14.

The planter row unit 61 includes a means for monitoring and controllinga depth of operation of the furrow opener 14. This means includes adepth sensor gauge wheel mount 54, a mechanical depth sensor linkage 55,and a depth sensor 56. The depth sensor 56 can be, for example, anencoder that provides a signal to the controller 36 based on the angleof rotation of the sensor linkage 55.

The planter row unit 61 can also include an adjustable downpressuresystem or a remote depth adjustment mechanism to vary the operatingdepth of the furrow opener 14 to adjust the planting depth. For example,the remote depth adjustment mechanism 57 illustrated in FIG. 7 includesa linear actuator 58 and linkage 59 coupled to the existing adjustmentarm on the planter row unit 61. The actuator 58 can be powered by ahydraulic, pneumatic, or electrical system.

The planter row unit 61 includes a system for measuring multiple soilproperties on-the-go as the planter traverses a field. This systemincludes, among other things, a soil moisture measurement device 15 cfor collecting soil moisture data from soil in the field at variousdepths, and a soil temperature measurement device 53 for collecting soiltemperature data from the soil at various depths (see FIG. 4). Thesemeasurement devices will provide growers with precise information aboutthe soil moisture and soil temperature within their seedbeds in order tomake better planting decisions and adjustments. For example, theinformation may be used to provide real-time adjustments of plantingdepth, and/or to make sure that the planting depth is consistent andoptimal for germination and emergence.

The soil moisture measurement device 15 c and soil temperaturemeasurement device 53 are both carried by the sensor module 15, asdescribed above. The sensor module 15 also includes a soil ECmeasurement device 15 c, and an optical module 15 a for measuring soilOM. The other parts of the planter row unit 61 having the sameconstruction as the system 10 described above are depicted in FIG. 7with the same reference numerals.

As illustrated in FIG. 7, the sensor module 15 follows behind the furrowopener 14 and also behind where seeds are dropped from the seed tube Tinto the furrow created by the furrow opener 14. The sensor module 15slides across the bottom of the furrow and presses the planted seedsinto the bottom of the furrow, while at the same time collecting soilmeasurements. This allows the sensor module 15 to function as a seedfirmer as well as a means for measuring soil properties.

FIGS. 8 and 9 illustrate another embodiment in which a sensor module 15′containing a soil moisture and EC measurement device 15 c′ and theoptical module is mounted between the furrow opener disks 20 so as to bepositioned in front of the seed tube T that drops seeds into the furrow.In this embodiment, the sensor module 15′ is formed as part of a seedtube guard located between the furrow opener disks 20 immediatelyforward of the seed tube T. This arrangement allows the sensor module15′ to collect its measurements from the soil at the bottom or sides ofthe furrow without disturbing the seed placement.

FIG. 11 illustrates an algorithm used by the controller 36 to controlplanting depth on-the-go during planting operations. The user can inputtarget planting depths that will be used by the system for variouspredetermined soil conditions, or the system can be programmed todetermine optimum planting depths based on various measured soilproperties. The controller 36 receives planting depth data from thedepth sensor 56 and soil moisture data, soil OM data, soil EC data, andsoil temperature data from the sensor module 15. The controller 36 usesthis data to determine the optimum planting depth in real time at thecurrent location. The controller 36 will then compare the calculatedoptimum planting depth to the current depth measured by the depth sensor56 and activate the depth adjustment mechanism 57 to raise or lower thefurrow opener 14 to cause the planter to plant at the optimum depth.

For example, when the soil moisture is determined to be insufficient forplanting at a very shallow depth, the controller 36 will cause thefurrow opener 14 to operate at a greater depth to increase the plantingdepth for planting in moist soil. For another example, when the soiltemperature is determined to be too cold at a relatively deep plantingdepth, the controller 36 will cause the furrow opener 14 to operate at ashallower depth to decrease the planting depth for planting in warmersoil. The controller 36 will use an algorithm with predeterminedparameters to automatically achieve an optimum planting depth in realtime based on the soil moisture, soil OM, soil texture, and/or soiltemperature data collected during the planting process.

FIG. 12 illustrates an algorithm used by the controller 36 on theplanter 60 for varying seeding rate of the planter on-the-go based onthe data collected by the sensor module 15. For example, the controller36 can be programmed with an algorithm or lookup table to determineavailable water holding capacity of the soil based on the measured soilEC, soil reflectance, and soil moisture. The available water holdingcapacity will provide a useful measure for soil productivity, and can beused to vary the seeding rate of the planter 60. The controller 36 cancontrol the seed metering mechanism 62 on-the-go during planting toincrease the seeding rate when the algorithm determines that theavailable water holding capacity of the soil is relatively high, and todecrease the seeding rate when the algorithm determines that theavailable water holding capacity of the soil is relatively low. Forexample, coarse soils having a water holding capacity of less than 1.0inches of water per foot of soil may be known to be less productive insome areas, and the controller 36 can be set to decrease the seedingrate when such soil conditions are detected. On the other hand, finesoils having a water holding capacity of greater than 2.0 inches ofwater per foot of soil may be determined to be the most productivesoils, so the controller 36 can be set to increase the seeding rate whensuch soil conditions are detected. Measures of soil productivity otherthan water holding capacity can also be used as a basis for varying theseeding rate.

The system for measuring multiple soil properties of the presentinvention provides significant advantages and improvements over existingsystems. Measuring soil moisture, soil EC, and soil reflectance at thesame spatial locations and depths as the implement traverses the fieldwill reveal additional information and increase the value of each sensorand the information it provides.

While the invention has been described in connection with specificembodiments thereof, it is to be understood that this is by way ofillustration and not of limitation, and the scope of the appended claimsshould be construed as broadly as the prior art will permit.

What is claimed is:
 1. A system for measuring multiple soil propertieson-the-go, comprising: an implement for traversing a field; an opticalmodule carried by the implement for collecting soil reflectance datafrom soil in the field; a soil EC measurement device carried by theimplement for collecting soil EC data from soil in the field; a soilmoisture measurement device carried by the implement for collecting soilmoisture data from soil in the field; and said optical module, said soilEC measurement device and said soil moisture measurement device arearranged to measure soil reflectance, soil EC and soil moisture atapproximately the same depth; wherein said soil EC measurement deviceand said soil moisture measurement device are arranged to measure soilEC and soil moisture in proximity to said optical module; wherein saidsoil EC measurement device and said soil moisture measurement devicecomprises at least one soil contact member carried by the implement,said at least one soil contact member being arranged for collecting bothsoil EC data and soil moisture data from soil in the field; and whereinsaid optical module comprises a hardened wear plate with a window, andwherein said at least one soil contact member protrudes from or isexposed on a bottom side of said hardened wear plate.
 2. The systemaccording to claim 1, wherein said at least one soil contact membercomprises two metal soil contact blades protruding from the bottom sideof said hardened wear plate.
 3. A system for measuring multiple soilproperties on-the-go, comprising: an implement for traversing a field;an optical module carried by the implement for collecting soilreflectance data from soil in the field; a soil EC measurement devicecarried by the implement for collecting soil EC data from soil in thefield; a soil moisture measurement device carried by the implement forcollecting soil moisture data from soil in the field; and said opticalmodule, said soil EC measurement device and said soil moisturemeasurement device are arranged to measure soil reflectance, soil EC andsoil moisture at approximately the same depth; further comprising ameans for calibrating said soil EC data based on said soil moisture datato minimize the effect of soil moisture variations on said soil EC data.4. A system for measuring soil properties on-the-go, comprising: animplement for traversing a field; a sensor carried by the implement formeasuring at least one soil property, said sensor comprising at leastone of an optical module for collecting soil reflectance data, a soil ECmeasurement device for collecting soil EC data, and a soil moisturemeasurement device for collecting soil moisture data; and a means formeasuring a depth of operation of said sensor on-the-go while saidsensor is measuring said at least one soil property; wherein said sensorfurther comprises an optical module arranged for collecting soilreflectance data from soil in the field; and wherein said optical modulecomprises a hardened wear plate with a window, and wherein said sensorfurther comprises at least one soil contact member for collecting soilEC data and/or soil moisture data that protrudes from or is embedded ina bottom side of said hardened wear plate.
 5. The system according toclaim 4, wherein said at least one soil contact member comprises twometal soil contact blades protruding from the bottom side of saidhardened wear plate.
 6. A system for measuring multiple soil propertieson-the-go, comprising: an implement for traversing a field; and at leastone soil contact member carried by the implement, said at least one soilcontact member being arranged for collecting both soil EC data and soilmoisture data from soil in the field; further comprising a phase lockloop connected to said at least one soil contact member for capturingboth soil EC and soil moisture readings simultaneously.